Line data Source code
1 : /*
2 : * Berkeley style UIO structures - Alan Cox 1994.
3 : *
4 : * This program is free software; you can redistribute it and/or
5 : * modify it under the terms of the GNU General Public License
6 : * as published by the Free Software Foundation; either version
7 : * 2 of the License, or (at your option) any later version.
8 : */
9 : #ifndef __LINUX_UIO_H
10 : #define __LINUX_UIO_H
11 :
12 : #include <linux/kernel.h>
13 : #include <uapi/linux/uio.h>
14 :
15 : struct page;
16 :
17 : struct kvec {
18 : void *iov_base; /* and that should *never* hold a userland pointer */
19 : size_t iov_len;
20 : };
21 :
22 : enum {
23 : ITER_IOVEC = 0,
24 : ITER_KVEC = 2,
25 : ITER_BVEC = 4,
26 : };
27 :
28 : struct iov_iter {
29 : int type;
30 : size_t iov_offset;
31 : size_t count;
32 : union {
33 : const struct iovec *iov;
34 : const struct bio_vec *bvec;
35 : };
36 : unsigned long nr_segs;
37 : };
38 :
39 : /*
40 : * Total number of bytes covered by an iovec.
41 : *
42 : * NOTE that it is not safe to use this function until all the iovec's
43 : * segment lengths have been validated. Because the individual lengths can
44 : * overflow a size_t when added together.
45 : */
46 : static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
47 : {
48 : unsigned long seg;
49 : size_t ret = 0;
50 :
51 : for (seg = 0; seg < nr_segs; seg++)
52 : ret += iov[seg].iov_len;
53 : return ret;
54 : }
55 :
56 : static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
57 : {
58 : return (struct iovec) {
59 : .iov_base = iter->iov->iov_base + iter->iov_offset,
60 : .iov_len = min(iter->count,
61 : iter->iov->iov_len - iter->iov_offset),
62 : };
63 : }
64 :
65 : #define iov_for_each(iov, iter, start) \
66 : if (!((start).type & ITER_BVEC)) \
67 : for (iter = (start); \
68 : (iter).count && \
69 : ((iov = iov_iter_iovec(&(iter))), 1); \
70 : iov_iter_advance(&(iter), (iov).iov_len))
71 :
72 : unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
73 :
74 : size_t iov_iter_copy_from_user_atomic(struct page *page,
75 : struct iov_iter *i, unsigned long offset, size_t bytes);
76 : void iov_iter_advance(struct iov_iter *i, size_t bytes);
77 : int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
78 : size_t iov_iter_single_seg_count(const struct iov_iter *i);
79 : size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
80 : struct iov_iter *i);
81 : size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
82 : struct iov_iter *i);
83 : unsigned long iov_iter_alignment(const struct iov_iter *i);
84 : void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
85 : unsigned long nr_segs, size_t count);
86 : ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
87 : size_t maxsize, unsigned maxpages, size_t *start);
88 : ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
89 : size_t maxsize, size_t *start);
90 : int iov_iter_npages(const struct iov_iter *i, int maxpages);
91 :
92 : static inline size_t iov_iter_count(struct iov_iter *i)
93 : {
94 : return i->count;
95 : }
96 :
97 : /*
98 : * Cap the iov_iter by given limit; note that the second argument is
99 : * *not* the new size - it's upper limit for such. Passing it a value
100 : * greater than the amount of data in iov_iter is fine - it'll just do
101 : * nothing in that case.
102 : */
103 : static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
104 : {
105 : /*
106 : * count doesn't have to fit in size_t - comparison extends both
107 : * operands to u64 here and any value that would be truncated by
108 : * conversion in assignement is by definition greater than all
109 : * values of size_t, including old i->count.
110 : */
111 139356 : if (i->count > count)
112 0 : i->count = count;
113 : }
114 :
115 : /*
116 : * reexpand a previously truncated iterator; count must be no more than how much
117 : * we had shrunk it.
118 : */
119 : static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
120 : {
121 : i->count = count;
122 : }
123 :
124 : int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
125 : int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
126 : int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
127 : int offset, int len);
128 : int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata,
129 : int offset, int len);
130 :
131 : #endif
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